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View Poll Results: What cowl fastening method
Hinge 47 40.52%
1/4 turn (Skybolt, Camloc, etc) 32 27.59%
Screw/nut plate 2 1.72%
Combo 32 27.59%
Other 0 0%
Dumb question. 3 2.59%
Voters: 116. You may not vote on this poll

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Old 07-08-2022, 07:24 AM
Freemasm Freemasm is offline
Join Date: Nov 2017
Location: Orlando
Posts: 958
Default Cowl Fastener/method choice

Bit of a nube question but I'm serious. What cowl fastening method did you use choose ? Why you settled on your choice (besides it was in the instructions)? Would you have done it differently? Would really like to hear from someone who's installed different options/maintained multiple.

Last edited by Freemasm : 07-08-2022 at 07:29 AM.
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Old 07-08-2022, 07:36 AM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 8,073

On the 6, I used screws top and bottom and hinges elsewhere. I didn't like what I read about hinges wearing out on the bottom and for the top I didn't like what I read about difficulty getting the pins out.

On the 10, I went full hinges, except used SS hinges on the bottom due to stress killing the stock hinges. I hear that the forged hinges also hold up, but the SS was cheap and readily available at McMaster in town.

The quick lock stuff looks nice, but cannot bring myself to spend $500 for it. Both builds were on a budget.

N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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Old 07-08-2022, 08:22 AM
jcarne's Avatar
jcarne jcarne is offline
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 2,405

I used hinges everywhere but I sure wish I had cams on the bottom at least. Them sons of Bs are sure expensive though.
Jereme Carne
Commercial ASEL; IFR
RV-7A Flying as of 03/2021
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Old 07-08-2022, 08:48 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,573

Several years before I started my RV-3B project, I had a hangar neighbor with an RV-8. He had a very great deal of trouble with his cowl hinges. Made an impression.

And I've got a C180 with the cowling screws, which dissuaded me from that.

The only thing readily available and thought-out are the 1/4 turn fasteners, so I'm using them. However I bought a brand which has since gone out of business, sigh. Nothing wrong with them, as far as I know, but still - orphans.

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Old 07-08-2022, 08:59 AM
Larry DeCamp Larry DeCamp is offline
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 1,291
Default Skybolt vs screws vs hinge

My 3 had hinge on sides and skybolt on firewall.
Hinges are a PITA and Rivets pop the filler over them. You could drill holes in the hinge flange and epoxy a glass tape over it to create an epoxy riveted stress relief. The wire needs to be undersized and ends secured with ugly clamps or complicated medallions.
Skybolts are nice, but you cannot get the cowl off if they remain secured in the part. You just remove and put in a cup and individually replace for assembly. Their main appeal for me is the ability to adjust for cowl surface alignment IF you leave a gap between the cowl and underlying structure ( ask me how I know..duh)

So, my new RV4 is all Skybolt. In hind sight, i would consider other quarter turn options or screws with SS washers The only negative to screws is vibration security. Blue loctite is a PITA and nutplates without tapping are also. My $.02
Larry DeCamp
RV3B sold
RV-4 fastback in process w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN
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Old 07-08-2022, 09:23 AM
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Rick_A Rick_A is offline
Join Date: Oct 2005
Location: Jacksonville, FL
Posts: 1,637
Default Would use more hinge if I was building today

I did Skybolt 1/4 turn fasteners on the firewall upper & lower cowl - except the bottom where I used screws. I used hinges to join the upper & lower cowl halves.

If I were building today, I would definitely use hinges on the vertical portion of lower cowl-to-firewall and would strongly consider ditching the Skybolts on the top cowl-to-firewall. I think the hinges give a better fit and look better.

The Skybolt fasteners do make it easier to remove the top cowl but if I had just stayed with the plans from Vans, I would have saved time and money.
Rick Aronow,
Flying 7A Slider;
Jacksonville, FL
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Old 07-08-2022, 09:49 AM
MacCool's Avatar
MacCool MacCool is online now
Join Date: Aug 2020
Location: central Minnesota
Posts: 1,487

The guy that built my airplane used Skybolt fasteners on the entire upper and lower cowling. I have found them to be excellent. They are very secure and very convenient.
RV-9A, 2011, bought flying
IO-320D1A (factory new), C/S
Dual Pmags
IFR equipped
AFS 5400/3500, G5, IFD440 navigator,
bunch of other stuff
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Old 07-08-2022, 09:54 AM
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wirejock wirejock is offline
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,883
Default Skybolts

I used Skybolts for several reasons.
The adjustment is number one. If you use them, add a shim between the flange and the firewall or fiberglass. Without it, the cowl may sit shy of even.
They do require more work. Read some tips. I have a document on my blog.
Larry Larson
Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog:
Donated 12/2022, plus a little extra.
RV-7A #73391, N511RV reserved
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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Old 07-08-2022, 10:09 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 4,029

I never liked the look of SkyBolt type fasteners so have stayed with hinges - but modified.

I use 1/8” SS pins on the top cowl to fuselage hinge instead of the smaller diameter pins in the plans. The smaller diameter pins are needed to make the bend, but if you take the 1/8” pins and carefully reduce the diameter of the last 10” or so they make the bend. What this does is reduce the slop in the top cowl hinge.

For the bottom cowl to fuselage hinge I use the much stronger MS20001P extruded hinge. The per plans hinge tends to break off eyes from vibration as they are fairly short. I’ve never had a problem using these extruded hinges.

Note - if not using extruded hinge on the bottom I recommend three #6 screws and associated plate plus nut plates on each side as substitute.

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Old 07-08-2022, 10:30 AM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 11,243

Opposite of Rick...I'd again use Skybolts on the entire firewall perimeter. I've dinged my hands too many times R&Ring upper cowl hinge pins. Skybolts are also used to drop the airbox shell.

The horizontal seam is a toss up. Current cowl is #8 screws, and a glass flange with nutplates on the lower cowl. The goal was to be pretty much air tight to limit excrescence drag. Really locks the cowl halves together too, no shake, no fretting. In and out is fast enough with a power screwdriver.

A #10 behind the prop on each side enters a nutplate in a 0.060 aluminum tab

Offset hinge will also close the air gap, i.e. hinge pin eyelets not on the split line. Use one hinge half with a wide flange.
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Dan Horton
Barrett IO-390
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